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Chauffe eau


Kel
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After advice from this fine forum that chauffe-eau's are the way to go for all our hot water needs, does anyone know of a web site that offers simple instructions on how to fit them?

Is it just a cold water feed from the mains and then run hot water off? and can this hot water connection feed all the showers, baths and sinks in one run?

We are turning a three storey town house into three seperate apartments so do we need three seperate chauffe-eaus? Each apartment will have two bathrooms,one with shower and hand basin and one with shower and bath and two hand basins as well as a kitchen sink.Will probably use the 300 litre capacity unit and these we are hoping, will be sited in the cellar.

There is space on the top floor for it's own seperate chauffe-eau, but would the others still pumped the water up to the first floor level?

Would much appreciate any advice
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You buy the Chauffe-Eau and a "Kit de Securite" or Groupe de Securite" which costs between 25 and 40 Euro.

The Kit has 2 flexible pipes and a safety valve that  MUST be fitted. The valve regulates the water pressure in the tank to 7 bar. You also get a drain that connects to 32mm PVC pipe for the regulation valve. This must run outside, not to a soil pipe.

The tanks are heavy - a 200L tank weighs 50kg empty and 250kg full. So consider where you fit it. You can get fully wall mounted ones or floor mount with brackets for wall securing.

200L Steatite Chauffe-Eaus cost about 110 Euro each, so they probably cost less than a single 300L tank! 3 Kits about 110 Euro, 3 jour/nuits and MCBs about 120 Euros. With pipe and sundries, I reckon you could do it for under 1000 Euros.

As far as capacity is concerned, I would buy 3 200L ones for each apartment. Put each one on their own seperate jour/nuit contactor so you can switch them off for long periods independantly.

The water pressure, and more importantly the flow, provided you use 16mm or greater pipe to supply the cold in and take the hot out, will be fine. You should have no problem at all with water flow on higher floors. Provided: you have good water pressure and flow incoming from the road, and you minimize the number of connections in the pipework, and keep the pipe runs as short as possible in good sized pipe.

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Opel fruit, are you really suggesting that one needs 3x200litres for EACH appartment? Seems like total overkill to me, unless you have half a dozen inhabitants, all of whom want to run 3 baths a day. You would need a fair sized room to put them all in too.

Brian.

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Just a minor correction (but very important) from Opel Fruits post above;

The Groupe de Securité is a safety valve that allows water to expand inside the tank and DOES NOT limit the pressure inside the tank . This should be done with a "reducteur de pression" pressure reducing valve  which can either be fitted at the tank or at the mains water intake position. They rarely come supplied with the kits these days, because not every house needs it's pressure reduced. 7 bar is far too high for any H & C water in a domestic situation.

Just a couple of other suggestions for the original poster. If space is a premium you could consider horozontal tanks which can be useful. Also if using copper connections, use an isolating dielectric joint at the tank inlet and oulets. These are an insulation coupler that stops corrosion forming between two dissimilar metals. Most places sell them with the tank accessories.

If you have a problem with the drain off from the GD securité, you can buy and fit a small expansion vessel which does not need a drain - usefull in some situations where there is no easy drain off point. Also buy stéatite units unless you have a water softener installed, as it will last a lot longer. Modern units of a good make also have anode protection by a system called ACI, so if you see this on the info , it is a good idea.

best Regards,

Paul

 

 

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Hmmm....

The safety valve does limit the pressure in the tank. If the pressure exceeds 7 bar, the valve opens and releases pressure. If you need to reduce the entire water pressure into the house, you can fit a pressure reduction valve. Quite why this is necessary.....!

French domestic sanitary water supplies run quite happily at 5-7 bar. The Generale d'Eau target mains supply to the water meter is 5 bar. All the installations we deal with are quite happy at this. Provided the installation is carried out well, no problem.

3 x 200L tanks will provide all the needs of each apartment and as I said are the cheapest solution. A 300L tank takes possibly 8-10 hours to fully reheat. There are many options. I have suggested the cheapest that will provide an almost guaranteed supply of hot water.... 

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In the last 8 years spent in France working on plumbing installations, all the French plumbers I've worked along side, and both the plumbing "stages" I've been on disagree with having  pressure that high. I've never found a domestic pressure more than 6 bars anyway, except once which was very near the pumping station.

The experts seem to disagree with you too;

 

From  "Comme Un Pro"  by Thierry Gallauziaux;

 

“ Les companies qui fixent la pression du réseau, soit environ 3 bars. Au –delà de 3.5 bars , afin d’eviter tout dommage, il est nécessaire de prévoir un reducteur de pression.'

 

From the «  Proffesional Guide Des Metiers de Batiment” by NATHAN;

 

‘L’eau est distribuée sous une pression de l’ordre de 2.5 à 3.5 bars mais peut osciller entre 2 et 4 bars selon l’emeplacement de la station de pompage par apport de l’abonée.

 

Une pression trop forte accélère l’usure des joints et aggrave les effets de la cavitation dans les canilisations, ce qui aboutit généralement à l’éclatement d’un raccord. Au –dessus de 4 bars , il est recommandé d’installer un détendeur’

 

I could find plenty more references confirming that generally a pressure of no more than 3 bars is sufficient for any domestic installation, and anything rising to the levels you suggest can damage installations, and cause excessive and unnecessary noise.

 

best regards,

 

Paul

 

 

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Whatever.

The mains pressure here varies from 4.5-5.5 Bar. Which is fine. Most mistakes are made by restricting flow. Most plumbers (excluding the one I work for!) have a major problem with understanding hydraulic theory and practice. But then again, most are close to retirement. Likewise, the heating "engineers" still use custom and practice they learnt 40 years ago....

I also note that those folk round here who use well water have their tank cut-out set to 4 bar...which when a fair draw is made reduces to a running pressure of about 3.5 Bar.

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Oh well, at least you've come down from 7 bar now which was the main point of my post.

Me thinks a bit flippant to disregard the experience of plumbers with a whole lieftimes experience of French systems

I agree many mistakes are made with restricting flow, usually in respect of incorrect pipe sizes, and bad installation practices , rather than pressure.

Shall we agree to disagree and for the benefit of the original poster and others  put the subject to bed for now?

Best regards,

Paul

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Well...er thanks..I think. It is now as clear as mud. Obviously I didn't stress the word "SIMPLE" strongly enough in my original question but thanks anyway for taking the time to reply. I have another 101 questions to ask but dare not in fear of getting even more confused.

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